The present invention relates to a package for enclosing a plurality of sheets of material, such as a stack of x-ray film sheets, with the package having a pouch and leader with different coefficients of friction to facilitate removal of the package from the stack of sheets in a magazine or the like.
It is known to provide a light tight package for holding a stack of sheets of x-ray film or the like. The package may comprise a pouch or bag for holding the sheets, and a leader that projects from an end of the pouch. Such a film package is placed in a magazine having a spindle, and the leader is attached to the spindle. Then the magazine is closed and the spindle rotated to strip the packaging material from the stack of sheets. Packages and magazines generally of the kind described above are disclosed, for example, in U.S. Pat. No. 5,019,849, issued May 28, 1991; in U.S. Pat. No. 5,048,686, issued Sep. 17, 1991 and in Italian Patent No. 1,062,043.
The related application cross referenced above also relates to a package of the kind holding a stack of film sheets and having a leader that is attached to a spindle in a magazine or the like for removing the package material from the stack of sheets. The package of such application has a leader fabricated from a material different from the material used in manufacture of the pouch. The leader is placed over the pouch and secured thereto so that it is positioned entirely over one face of the pouch. U.S. Pat. No. 5,048,686, mentioned above, states at column 4, lines 25-29 that the leader or flap of a package can be made from a material that is stronger and more tear-resistant material than the pouch.
Because the pouch of such a package is pulled away from the stack of sheets along both the top and bottom of the stack, the pouch needs to slide easily relative to the sheets to avoid displacement of the sheets during removal of the pouch. Also, the trailing end of the pouch is pulled through a light lock in some magazines, and the pouch needs to slide easily through the light lock. On the other hand, the leader of the package needs to be tough and durable and also be able to be gripped by the spindle during rotation of the spindle for removing the pouch from the stack of sheets. As a result, the physical characteristics desirable for the pouch to differ from the characteristics needed for the leader.